Add m_sum, m_zero, m_none
Import le_kw
Add put_in_database
Use put_in_database
Reduce get_row_of_samples
Remove get_row_of_samples
Reduce get_row_key
Remove get_row_key
Reduce sample_key
Reduce all_samples
Add cnt_none
Rebuild cnt_none
Add cnt_zero
Add sum_of_not_nones
Add v_none, v_zero, v_sum
Add v_none, v_zero, v_sum
Protect against empty string from Excel
Protect against empty string from Excel